Doug MacKinlay, owner of Diamondback Police Supply, said he sent Mark Kelly a refund last week on the AR-15 type weapon after learning the purchase was not for personal use but meant to highlight the need for gun control.

Kelly, who along with his wife is a top campaigner for curbs to military-style weapon ownership, had not yet taken possession of the semi-automatic rifle.

In a posting on Facebook on Monday, MacKinlay said: “While I support and respect Mark Kelly’s 2nd Amendment rights to purchase, possess, and use firearms in a safe and responsible manner, his recent statements to the media made it clear that his intent in purchasing the … rifle from us was for reasons other then for his personal use.”

“In light of this fact, I determined that it was in my company’s best interest to terminate this transaction prior to his returning to my store,” he added.

Both MacKinlay and Kelly could not be reached for comment.

A constitutional lawyer said there is nothing in the Constitution that bars the gun store owner from taking such action.

“The Constitution wouldn’t apply in this case. This is a private gun store owner,” said Paul Bender, dean emeritus and professor at the College of Law at Arizona State University.

Kelly, who with Giffords formed a lobbying group focusing on gun violence, drew immediate criticism from conservatives on social media after the gun buy earlier this month from the store in Tucson, Ariz.

Kelly’s group, Americans for Responsible Solutions, has been vocal on the need to ban high-powered semiautomatic weapons such as the AR-15 as well as high-capacity magazines. The group also wants universal background checks for all gun buyers.

MacKinlay said the rifle would be donated to the Arizona Tactical Officers Association and sold at an auction, with the proceeds used to buy its members equipment. He said the store would also give $1,295 — the rifle’s sale price — to a child gun safety program.

Giffords was shot through the head in January 2011 when a gunman opened fire on a constituent event in Tucson, killing six people and wounding a dozen others. She stepped down from Congress a year later to focus on her recovery.

She and Kelly launched their gun control campaign in the wake of an assault rifle attack on a Connecticut elementary school in December that killed 26 people, including 20 schoolchildren.

The group is also calling on Congress to mandate universal background checks for all gun buyers, and seeks to raise $20 million for the 2014 congressional elections — matching the powerful National Rifle Association’s spending in last November’s election.